Fairy shrimp are small crustaceans only distantly related to lobsters, crabs, and the shrimp we commonly find on our dinner tables. Most species are rather small, seldom larger than an inch in length. Adapted to temporary habitats, fairy shrimp eggs are able to withstand years of complete dryness and need as little as 30 hours of inundation to initiate development. Capitalizing on seasonal rainfall and inundation, fairy shrimp become numerous and are a high protein source for fish and shorebirds. It is likely that this fairy shrimp was hatched in a temporary pool of water or tributary and then swept into the mainstem Missouri River by heavy spring rains.
Sampling the Missouri River with fine mesh nets, known as ichthyoplankton nets, results in catching organic matter, fish eggs, larval fish, and macroinvertebrates. Macroinvertebrates, such as this fairy shrimp, are organisms that lack a spine, are large enough to be seen with the naked eye, and are an important part of the food chain, especially for fish. Macroinvertebrates in the Missouri River can be found attached to rock surfaces, buried in the mud, or drifiting downstream. Sampling drifting invertebrates with ichthyoplankton nets can help determine what macroinvertebrates are available and how temporary wetlands and connected floodplains contribute to the food chain at these locations. Where river currents carry and deposit invertebrates may partially explain why fish are found where they are.
Contributions by Barry Poulton & Aaron DeLonay